Method of removing gases from molten light-metals such as aluminum and its alloys



June 16,1931.

METHOD OF REMOV and Patented June 16, 1931 1 UNITED STATES PATENT OFFICEWILHELM T0131, 01 LAUTAWERK/LAUSITZ, GERMANY METHOD REMOVING GASES FROMMOLTEN LIGHT-METALS SUCH AS ALUMINUM AND ITS ALLOYS Application filedJuly 29, 1929, Serial No.

My invention relates to a method of removinggases from molten.llght-metals such as aluminum and its alloys.

It is a known fact, that light-metals such as aluminum andaluminum-alloys cannot be cast in molds immediately upon the productionthereof, for the reason that they contain comparatively considerablequantities of gases, which will be detrimental to the cast cases where amust be substantially free from blow-holes or ust in accordance with theamount of metal under treatment.

This method however does not give satisfactory results; even if themolten metal is allowed to stand for a very prolonged length of time, aperfect liberation of gases cannot be obtained in this way especially inthose particular casting necessarily pores.

The chief object of the present invention is to provide a method whichwill overcome this difficulty.

" present invention, consists in agitating or moving the layer or volumeof air located on top and above the molten metal and preferably causingthe same to circulate without allowing any fresh air to mix therewithand without changing to a perceptible degree the temperature of themolten metal or the atmosphere pressure. I

In the accompanying drawing forming a part of this specification andshowing .for purposes of exemplific'ation a preferred form of theapparatus for carrying out the invention the only figure is a View invertical section of a melting furnace illustrating somewhatdiagrammatically the means employed for. the present purpose.

In the drawing the character a designates the furnace provided with acharging door I) and a heating spiral a in a recess provided in Withthis object in view the 382,000, and in Germany .Tune 12, 1928.

the top structure of the furnace for the accommodation of the saidspiral. In the upper portion of the furnace there is a circulatingchannel or passage 6 constituted by a vertical duct at one end of thefurnace chamber, a similar duct at the .other end. thereof. and ahorizontal tubular passage way interconnecting the said two ducts so asto form, together with the furnace chamber, a closed circuitous Way forthe circulation of the air and gases enclosed in the furnace chamber. Inthe horizontal passage-Way preferably at a point midway between its twoends a fan f is inserted and arranged to be in connection with suitablemeans (not shown) for operation. 1

It will be seen that when the fan f is -caused to revolve the air andgases contained in the furnace chamber will circulate through thepassage or channel 6 as indicated by the arrows. Obviously any otherappropriate means may be employed for bringing about the circulation ofthe gaseous matter in the furnace, just as any other suitableair-agitating means such as a pump or the like may be substitutedfointhe fan 7. What I claim is: v I

1. A method of freeing a bath of 'molten lightmetals such as aluminumand aluminum alloys from gases occluded therein, which consists incirculating the gases lo-' cated above the molten metal, without passingthem through the metal and without substantially changing their volumeand the temperature of the molten metal, and preventing the admission offresh air to the furnace. 2. An apparatus for freeing a 'bath of moltenlight-metals such as aluminum and heating means in the said chamber, acon-' duit for the circulating gases connecting an exit-opening in themelting chamber to an inlet-opening of the same in this circulationconduit.

3; An apparatus for freeing a bath of molten light-metals such asaluminum and aluminum-alloys of gases occluded therein, comprisingaclosedmelting furnace with a and a fan arranged melting chamber at thebottom thereof, an

electrical heating means in the said chamber and above the metal-bath, aconduit for the circulatin gases connecting an exit-opening 5 in the meting chamber to an inlet-opening of the same and a fan arranged in thecirculation conduit.

In testimony whereof I afiix my signature.

HELM TODT.

